1) The presentation discusses the effect of initial surface condition on pool boiling of nanofluids. Recent research has found that nanofluid heat transfer performance is greatly affected by nanoparticles depositing on the heated surface during boiling. 2) The current research uses new precision machining techniques to create consistent surface textures and surfactants to enhance nanofluid stability and prevent nanoparticle deposition. Experimental results show that surfactant addition eliminates deposition and improves heat transfer. 3) Heat transfer is also influenced by surface roughness, with rougher surfaces enhancing boiling. However, when nanoparticle size is larger than surface roughness features, deposition does not occur and heat transfer is improved with or without surfactant addition. The research aims

1. Presented by: Mohamed Hamda
M.A.Sc Candidate
Supervisor: Dr. M. Hamed
On The Effect of Initial Surface
Condition on Pool Boiling of
Nanofluids

2. Outline
• Pool Boiling.
• Nanofluids.
• Literature review.
• Recent Research in TPL.
• Current research.
• Conclusion.
• Future work.
• Publications.
2

3. Why Pool Boiling?
• Free Convection - Water: 20 - 100 (W/(m2K))
• Forced Convection - Water: 50 - 10.000
(W/(m2K))
• Boiling Water : 3.000 - 100.000 (W/(m2K))
Boiling Heat transfer coefficients are the highest
among different heat convection mechanisms.
6

4. Pool Boiling Curve
7
* Heat and Mass Transfer: Fundamentals & Applications,Fourth Edition, Yunus A. Cengel

5. Thermal conductivity of different
materials
Liquids Metals
k - W/(m.K)
Steel, Carbon 1% 43
Aluminium 205
Copper 401
k - W/(m.K)
Alcohol 0.17
Engine Oil 0.15
Water 0.58
8
• The thermal conductivity of liquids is three orders of
magnitude less than of metals.
• The idea is to increase the thermal conductivity of liquids.

6. How can we do that?
• Powder of metal has particles of certain size
(10 ~ 100 nm) dispersed into liquid.
• This mixture is now called Nanofluid or
Nanoparticles suspension.
9

7. Is Nanofluid a novel idea?
• Maxwell model (1881)
– Effective thermal conductivity increases with the
volume fraction of the solid particles as well as the
ratio of the surface area to volume of the particle.
– Confined to millimeter-sized particles.
– Not practical (severe clogging problems).
• Lee, Choi and et al. (1999)
– Reported 20% increase in the thermal conductivity of
CuO nanoparticles (10 nm) suspended in ethylene
glycol.
10

8. Literature Review
11
* O. Ahmed, M.S. Hamed, Experimental investigation of the effect of particle
deposition on pool boiling of nanofluids

9. Recent Research in TPL
12
Researcher
(Year)
Experiment
Type
Ra (nm)
Concentration
%
Nanofluid
Material
Particle
size
pH Remarks
Osama
Ahmed
(2011)
Pool Boiling
100 ~
150
50
0.01
0.1
0.5
Al2O3
40 ~ 50
nm
5 and
6.5
Enhancement
&
deterioration
Ahmed
Abd El-
hady
(2013)
Pool and Jet
Impingement
Boiling
20, 80
and 420
0.005
0.01
Al2O3
CuO
10 nm
50 nm
6.5
Enhancement
&
deterioration

10. Findings from Literature Review
13
• Contradicting results!
• Heat transfer deterioration is always noticed with
nanoparticles deposition on heated surface.
• Most enhancement results were reported for
heated wires.
• Deterioration is more likely to happen with flat or
horizontal heated surfaces.
• Heater geometry affects Nano fluid heat transfer.

11. What is new in this research?
Old technique
• Polishing by emery paper.
• Inconsistent surface texture.
New technique
• High precision machining.
• Consistent surface texture.
14
1. Surface Preparation

12. What is new in this research?
2. Using surfactants to enhance the stability of
nanofluids.
• Surfactant is a compound that lowers the surface
tension.
• Sodium dodecylbenzenesulfonate (SDBS).
15

13. Nanofluid Preparation
• Deionized water.
• Al2O3 , Particle size =40 nm ,(0.05%wt)
• Sodium dodecylbenzenesulfonate “SDBS”
(0.1%wt).
19
1. Li et al, Evaluation on dispersion behavior of the aqueous copper nano-
suspensions.
2. Wang et al, Influence of pH and SDBS on the Stability and Thermal
Conductivity of Nanofluids.

14. Experimental Setup
20
q”

15. Boiling curves on Ra=60 nm
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 2 4 6 8 10 12 14
q”MW/m2
ΔT
Water Before
NF,SDBS(0.1%)
23

16. Boiling curves on Ra=60 nm
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 2 4 6 8 10 12 14
q”MW/m2
ΔT
Water Before
NF,SDBS(0.1%)
NF,SDBS(1.0%)
24

17. Boiling curves on Ra=60 nm
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 2 4 6 8 10 12 14
q”MW/m2
ΔT
Water Before
NF,SDBS(0.1%)
NF,SDBS(1.0%)
Water After
25

18. Boiling curves on Ra=60 nm
• Heat transfer enhancement in natural convection
regime and deterioration in nucleate boiling
regime.
• Nanoparticles deposition has been noticed.
• ONB has been delayed using Nanofluids.
• Increasing SDBS concentration has effectively
eliminated deposition and thus heat transfer
enhancement is achieved.
• No deposition was confirmed by boiling pure
water on the same surface from the Nanofluid
experiment.
26

19. Water boiling curves
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 2 4 6 8 10 12 14 16 18 20
q”MW/m2
ΔT
Ra=6 nm
Ra=60 nm
27

20. Boiling curves on R=6 nm
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 2 4 6 8 10 12 14 16 18 20
q”MW/m2
ΔT
Water Before
NF,SDBS(0.1%)
NF,SDBS(0.0%)
Water After
28

21. Boiling curves on R=6 nm
• Heat transfer is affected by the surface
roughness.
• SDBS accelerates Onset of Nucleate
Boiling(ONB).
• Heat transfer enhancement is achieved with
and without adding SDBS.
• No deposition is noticed.
• Nanoparticle size is larger than surface
roughness.
30

22. Boiling at 0.2 MW/m2
Nanofluid Water
31

23. Boiling at 0.4 MW/m2
Nanofluid Water
32

24. Boiling at Critical Heat Flux
Nanofluid Water
33

25. Conclusions
• Modern manufacturing technologies
introduced new types of fluids.
• Nanofluid heat transfer is greatly affected by
initial surface conditions.
• Surfactants enhance stability of Nanofluids.
• Heat transfer deterioration results from
Nanoparticles deposition.
34

26. Future Work
• Develop a matrix to quantify the contribution
of each component used in Nanofluid
preparation.
• Test the performance of Nanofluid on very
rough surface.
• Understanding the Nanofluid interactions with
active nucleation sites using engineered Nano-
indentation.
35

27. Publication
• N.A. Almalki, M. Hamda, M. S. Hamed, On The Effect
of Initial Surface Condition on Pool Boiling of
Nanofluids,9th International Conference on Boiling
and Condensation Heat Transfer, April 26-30, 2015 –
Boulder, Colorado. (Extended Abstract Accepted)
36

28. Acknowledgement
• Alex Yip
• M. Tauhiduzzaman

29. Thanks for your attention.
hamdamr@mcmaster.ca